1. Field of the Invention
This invention relates to packet processing.
2. Related Art
In a computer network for transmitting information, messages are received by each router (or switch) at an input interface and retransmitted at an output interface, so as to forward those messages onward to their respective destinations. Each router performs a lookup operation for each message it encounters, in which the router determines from the message to which output interface the message should be forwarded.
One problem in the known art is that the lookup operation can be relatively complex, and can use a relatively large amount of processor resources. For example, the lookup operation can be complicated by concurrently determining one or more of the following:                which output interface is the closest, within a defined network topology, to the specified destination;        whether the message is unicast or multicast, and in the latter case, from which input interface the message was received;        whether the message is authorized to be forwarded by this router from its specified source, and whether the message is authorized to be forwarded by this router to its specified destination;        whether the message should be forwarded to a selected output interface for quality of service considerations, security considerations, or other administrative considerations;        whether the message should be counted, measured, or otherwise accounted for, concurrently with forwarding.        
Known responses to this problem include (1) to provide greater processing capability, so as to make up for the processor load on the router, (2) to provide only some of these concurrent services, or to provide them only a reduced functionality. While these responses achieve the goal of routing messages in a forwarding network, they have the disadvantage that added services introduce additional load on the router processor and slow down the router.
Accordingly, it would be advantageous to provide a method and system for packet processing that is not subject to drawbacks of the known art.